1. Field of the Invention
The present invention relates to a process of cracking a plastic material into useful components and recovering them. In addition, the present invention also relates to an apparatus of carrying out the process according to the present invention. The term "plastic material" is intended to mean, in addition to, a plastic material such as a general-purpose plastic material and an engineering plastic material, a rubber material. Such a plastic material may be of any type, for example, a waste material.
2. Description of the Related Art
Japanese Patent Kokai Publication No. 53-60974 describes a process in which a waste plastic material such as a polyvinyl chloride plastic material is supplied into a retort, which is heated to a temperature of not higher than 350.degree. C. so as to thermally decompose the material; a distilled organic material comprising a plasticizer and its cracked materials are burnt off while produced chlorine gas is recovered; and activated carbon is recovered from a residue comprising carbonaceous material after cracking.
When a chlorine containing plastic material such as a polyvinyl chloride is thermally decomposed and formed chlorine gas is recovered as described above, effective source utilization is achieved by reusing the recovered chlorine gas. However, since a plasticizer mainly comprising a phthalate ester contained in the plastic material cannot be effectively cracked, it is burnt off, for example, in a low temperature gasification combustion process.
Thus, there is a problem that an industrial useful material such as phthalic anhydride which constitutes the phthalic ester plasticizer cannot be utilized by the process as described above, so that not only sources are wasted but also such an effective material is degraded due to contamination by the plasticizer and its cracked components. In addition, an aliphatic hydrocarbon produced with cracking of the plasticizer such as octanol is reacted with a chlorine compound such as hydrogen chloride from the plastic material, whereby a chlorinated hydrocarbon such as octyl chloride is produced of which disposal causes a problem.